Cast Iron or Bronze?

I'm slowly working through my first Norton rebuild , 1971 Roadster I got in parts a couple years ago. It's time to rebuild the head.
I've done quite a lot of head work over the years but all of it on Harleys. The longest lasting HD combo was nitrided steel valves W/ cast iron guides. (Harley or Rowe valves and HD guides, seals on intake only)
Whenever we used bronze guides (Rowe) they were mated with stainless steel valves (Manley). As I remember, the bronze/stainless combo required a bit more clearance on the exhaust to prevent sticking a valve (live and learn,eh).
All of this is Harley specific and may not be directly applicable in a Norton context.
I've purchased a set of Kibblewhite valves.
In your personal experience, what is the most compatible guide for these valves ? What material/ brand name/ supplier and what guide to stem clearance have you used with good results.
Thanks for your time.

Alum.Bronze were the most expensive . :mrgreen:

My understanding is that bronze guides expand and contract at a similar rate to the aluminium head as it heats up and are therefore less likely to come loose than cast iron ones which expand less than the head.

The black coating on Black Diamond valves is designed to be used with the Kibblewhite bronze guides- it is a good match. Jim

comnoz said:

The black coating on Black Diamond valves is designed to be used with the Kibblewhite bronze guides- it is a good match. Jim

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Also Black Diamond valves in combination with K-lines in the original cast iron guides(only 850) works great.

Beware of replica BD valves! I run into so called BD valves (also black coated but around half the price). Only buy them in original Kibblewhite packaging to be sure you get the best valves available for your Norton.

Having used both at one time or another, the original Norton cast iron guides were harder wearing than the bronze or maybe I again brought some inferior High Dural 5 bronze guides made by that man Paul Dunstall :!: